From two cops now - they can't confiscate for a clean, controlled wheel stand, they can for stoppies (breaking traction with a driving wheel). But let's face it - on the side of the road, cop's pissed and smells the blood in the water, he can do what he wants. You can argue when it gets to court, but by then it's done and you have your bike back anyway.
Wheelies, apparently, are seen as a section 60 (ie reckless) offence. But there's plenty of cases where time and place have come together with a half reasonable magistrate and the charge has either been dismissed or dropped to careless.
Apparently the tyre-warming weave up the street can also be tagged for careless...

fucking insanity.